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Putting the V in HVAC!

Here is a Trane XL20i heat pump system my guys installed last week with a Lifebreath Heat Recovery Ventilator and we sealed and tested the ductwork.http://youtu.be/VyJTeS0o02c
Customer has very bad allergies and a special needs child that needed very pure air as well as very tight temperature controls. The special needs child already is doing better with the new air quality!

Looks like your guys did a great job as always, Travis. Nice work. The XL20i truly is a great unit. I assume you forwent the communicating control due to the Prestige's ability to control the ventilation.

Two compressor heat pump. Didn't know about that. One refrigeration circuit or two? Operated as a two stage by TStat or controlled by what? Inquiring minds want to know.

One circuit. Compressor staging is controlled by the thermostat as in most 2-stage systems. I have a 20i controlled by the Trane TCONT900 thermostat (similar to the VisionPRO IAQ). Second stage (4 ton compressor) is engaged when load is at ~90% of 1st stage capacity, or when trying to recover (i.e., change setpoint a couple degrees) and more capacity is needed. I'm pretty sure the Prestige uses a similar or identical algorithm. Most of the time the low stage compressor can handle the load with longer runtimes resulting in better comfort. On warmer/cooler days, second stage compressor will cycle to assist in maintaining setpoint. Check it out -- it works very well when sized properly.

One circuit. Compressor staging is controlled by the thermostat as in most 2-stage systems. I have a 20i controlled by the Trane TCONT900 thermostat (similar to the VisionPRO IAQ). Second stage (4 ton compressor) is engaged when load is at ~90% of 1st stage capacity, or when trying to recover (i.e., change setpoint a couple degrees) and more capacity is needed. I'm pretty sure the Prestige uses a similar or identical algorithm. Most of the time the low stage compressor can handle the load with longer runtimes resulting in better comfort. On warmer/cooler days, second stage compressor will cycle to assist in maintaining setpoint. Check it out -- it works very well when sized properly.

TXV or ElectronicXV?

"The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
- Alexis﻿ de Toqueville, 1835

The new Hyperion air handlers have EEVs. All 20i outdoor units have EEVs as well.

Thanks. Figured as much. These systems must cost a pretty penny. I suppose the energy saving must really be there to justify such a complicated set-up. I guess these systems can replace the dual capacity compressors made a while back by Bristol or the two speeds made by Lennox a number of years ago.

"The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
- Alexis﻿ de Toqueville, 1835

Sorry, I have not had time to respond to my own post, I had some urgent health matters this weekend.

We did not use a communicating system for a couple of reasons. First, the Trane XC80 is not a stock item at our distributor and for them to get me one its usually a 4 week lead time. I only wait the 4 weeks if it will be zoning down the road or the customer really wants communicating and an 80% furnace. We did have the option of the XC95 but with Portland's mild climate there would never be a payback on going from the 80 to 95 furnace with this high efficiency heat pump. We also did not go communicating because the trane communication system does not allow for ventilation so it was easier to control via a Prestige HD with good ventilation and ASHRAE 62.2 controls.

Yes the system does cost a pretty penny and usually it is not energy savings that justify the cost, its the added comfort. 4 Stages of heating in a 1400 sq foot house with sealed ductwork can be very nice. The homeowners have already commented that they don't hear anything, they never hear the heat pump, the ventilation, the furnace, the airflow. Its all so quiet and the house performs much better which was very important for their special needs family member. Its about quality of life first and savings second. We usually put in a couple of these per month but I don't think we have installed one for a while with how much Geothermal we are doing, lots of people are going for the variable capacity geothermal with boring/drilling instead of an XL20i and lots of Greenspeed competition.